Conversion of organic hydroxy compounds to carbonyl derivatives



Patented June 29, 1954 CONVERSION OF ORGANIC HYDROXY COM- POUNDS TO-CARBONYL DERIVATIVES Edward H. Carter and Louis E. Sartain, Kingsport,Tenn., assignors to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey No Drawing. Application November 22, 1952,Serial No. 322,152 1 7 Claims.

This invention relates to the conversion of organic hydroxy compounds tocarbonyl derivatives. More particularly, this invention is concernedwith an improved copper-silver compacted screen type catalystparticularly useful in processes for the conversion of ethyl alcohol toacetaldehyde.

This application is a continuation in part of our application Serial No.111,568, filed August 20, 1949, now abandoned, which in turn is acontinuation in part of our application Serial No. 748,843, now PatentNumber 2,482,742.

As shown by various publications, such, for example, as IndustrialCatalysis by Green (1928) pages 386 and 387, in the past copper andsilvercontaining catalysts have been used industrially indehydrogenation reactions, such as in the conversion of methyl alcoholto formaldehyde. As shown in the Catalytic Oxidation of OrganicCompounds in the Vapor Phase by Marek and Hahn (1932), pages 44 and 45,the catalytic ac-- tivity of such catalysts diminishes after a certainperiod and heretofore restoration of activity has been accomplished byoxidation of the catalyst with hot air. In the industrial use of thistype of catalyst it has been customary to obtain a relatively pure metalsuch as substantially pure copper or silver and fabricate the catalystfrom these materials. The catalyst has heretofore been fabricated intovarious forms and sizes, including pellets and screens.

In the prior use of a catalyst, such, for example, as a copper or silverscreen catalyst fabricated from a good grade of metals, it has beenobserved that, in some instances, the new catalyst, when inserted in thecatalytic converter, might start to function very easily, whereas inother instances it required much longer periods of ancillary heatingbefore the catalyst attained suificient temperature to functionself-sufficient- 1y. Also in the operation of such prior art catalysts,while at the onset of the process the catalyst gave good conversion,after a period of operation, which might not be constant or uniform foreach catalyst, a decrease of efliciency was indicated, this beingevidenced by reduction in the amount of conversion per pass and/or by anincrease in the decomposition products in the effluent materials. Inother words, considering specifically the treatment of ethyl alcohol incontact with a catalyst, in prior art operation, using the usualuntreated copper and/or silver catalyst, in some instances thepercentage of, acetaldehyde in the efliuents dropped 10% or after thecatalyst had been used for a relatively short period. Also, in someinstances decomposition increased after extended usage, as indicated byan increase tents of the effluent gases from less than one per cent upto several per cent.

Furthermore, in the processing of hydroxy compounds, such as theconversion of ethyl alcohol to acetaldehyde and involving contact ofthese materials with copper and/or silver catalyst, it has been observedthat both the conversion and the amount of decompositionresulting fromthe use of a catalyst derived from a given source are likely to difierfrom the conversion and decomposition obtained with a similar catalystderived from a different source. Likewise, while one catalyst mightoperate for several months, in the instance of another catalyst,presumably from similar materials and constructed in the same physicalform, the amount of decomposition products in the efliuents mightincrease to such a value that the efficiency of the process would beimpaired in that too great a portion of the feed materials would bedecomposed to carbon monoxide and carbon dioxide.

We have found, in accordance with the inven-- tion described in detailherein, that an improved type of catalyst may be prepared which ishighly advantageous in that the catalyst is more uniform and the resultsobtained therefrom more consistent. Also our catalyst, newly chargedinto a converter, permits relatively fast starting of the converter andoperation over longer periods of time than heretofore and without thequantity of decomposition products increasing to an undesired value. Wehave found that our process of preparing and assembling the improvedcatalyst described herein may be applied, not only to new catalystmaterial, but also that old, or used, catalyst material treated in acomparable manner may be restored to activity and uniformity repeatedlywith results which are comparable to those obtained with new catalystmaterial which has initially been treated in accordance with the presentinvention.

This invention accordingly has for one object to provide an improvedcatalyst material particularly suitable for use in converting organichydroxy compounds to carbonyl compounds. A further object is to providean improved copper and/or silver catalyst which is easier to use thansimilar known catalysts when initiating a reaction, gives more uniformand duplicable operation, and has extremely long life. A still furtherobject is to provide an improved copper and/or silver compressed -screentype of catalyst. Another object is to provide a method of renderingmore uniform and efiicient a metallic screen type catalyst, which hasbeen used. Still another object is to provide a method of treatingcatalyst screens wherein the metal comprising the screens may have beenobtained from various sources or is of various conditions of purity, toobtain catalytic material that is relatively uniform as indicated byduplic'able results when'the catalyst materials are used in parallelconverters. A further object is to provide an improved and rela tivelyuniform process for converting lower aliphatic alcohols to theircorresponding carbonyl derivatives. A specific object of the inventionis to provide an improved process for'converting ethyl alcohol toacetaldehyde. Other objects will appear hereinafter.

These objects are accomplished by the following invention which is basedupon the discovery that by treating either a new catalyst or usedcatalyst screen by an annealing process described in detail herein thatthe catalyst screens may be greatly improved, as evidenced by moreuniform results and less decomposition products in the efiluents inprocess of using said catalyst screens, even after much longer periodsof catalyst utilization than heretofore employed in the prior art. Itwill be observed that our method of heat treatment is considerablydifferent than the methods referred to above of treating catalyticmaterial with blasts of hot air or other oxidizing media. It is alsodifferent than the treatment of catalytic screens with a blowtorch andthe like in that such prior treatments with heating may give catalystscreens of nonuniform activity. That is, catalyst screens treated withblowtorches and welding torches may tend to develop hot spots on thesurfaces, which spots may be overactive at some points, thereby causinggreater losses, probably through decomposition of feed material tocarbon monoxide and carbon dioxide at the hot spots in subsequent use ofthe screens so treated, as well as otherwise contributing to uneventemperature conditions over the surface of the catalyst;

We have found that catalytic material of the class described, either newor used catalyst screens, for example, may be materially improved by asystem of heating or annealing said catalyst screens over a period ofpreferably more than three hours and usually not longer than fifteenhours and for a temperature and period which is insufficient to softenthe catalyst. Usually a temperature of from about 700 F. to not greaterthan about 1500 F. is satisfactory, namely, a temperature which,depending upon the length of the heating, would not be high enough tounduly soften the catalyst. We have found it pref erable to employseveral alternate layers of catalyst screens, as described in detailhereafter and, after the catalyst screens have been properly heated inaccordance with the present invention, they are preferably compactedsomewhat by pressure so that the height of the alternate layers ofscreens is reduced by this compacting by, say, 2% to That is, if theheight of the alternate catalyst screens were initially about 4 inchesit would be compacted by suifr cient pressure to reduce the height afraction of an inch, or, for example, to around 3 inches. We havefurther found that catalyst screens of the type described, even afterthey have been used a year or more, may, in accordance with the presentinvention, be retreated one or more times and thus restored to acondition comparable to their initial condition.

Our invention is set forth in further detail by reference to thefollowing description of the treatment of an alternate copper and silverscreen type catalyst.

A relatively good grade of copper and silver screening made up of about.06-.07 diameter wire of between 6 to 10 mesh'was obtained fromcommercial channels. This wire was cut into a configurationcorresponding to the internal configuration of the catalytic converterinto which thematerial was to be inserted. However, before placing thescreens in the converter they were given a treatment, in accordance withthe present invention, as follows:

The copper screens were placed in an iron rack and likewise the silverscreens were placed in another similar iron rack. The iron rackscontaining the screening were inserted into a cold annealing furnace sothat the racks containing the catalyst screens were positioned about twofeet above the bottom of the furnace. The furnace employed for thetreatment was similar to the usual metallic annealing furnace and wasmade up of ceramic firebrick which enclosed the furnace space. Thefurnace was heated from thebottom by a series of burners using keroseneor other light oil as a fuel. Each burner was provided with an inlet forsufficient air (some excess) for the complete burning of the kerosene orother fuel. The bottom of the aforementioned furnace was provided withuniformlyspaced inlet ports from the burner chamber so that thecombustion products passed into the interior of the furnace and aroundthe catalyst screens contained in the racks aforementioned. The upperportion of the furnace was provided with conventional outlet ports whichdischarged to a stack or otherwise to the atmosphere for permitting theproducts of combustion to escape from the interior of the furnace.

After placing the screens in the furnace, combustion was initiated sothat the inside temperature of the furnace immediately above thescreens, as determined by thermocouples positioned immediately above thescreens, was rapidly raised to 1,000 F. The temperature was controlledat this value, by control of the supply of fuel and oxidizing gas, forapproximately seven hours. The furnace was then allowed to cool toatmospheric temperature and the screens removed. The surface of thescreens was slightly oxidized and a fluffy coating of material whichanalyzed principally iron oxide was dusted off with a compressed airhose.

The catalyst screens thus treated were assembled in a stack comprisingfirst several layers of silver screening, then in alternate layers, oneor two layers of the copper or silver screen, until the alternate layerswere stacked several inches high. This stack of catalyst was thencompressed so that its initial height was reduced by approximately 2% to6%. The compressed alternate layers of catalyst screening were thenplaced in the usual converter. If desired, the compressing may beaccomplished in the converter.

The improved results obtained by using catalyst material so treated inaccordance with the present invention will be apparent fromconsideration of the following examples.

Example I In this example a comparison is made of the greater ease instarting up a catalyst unit containing the processed copper-silverscreen of the present invention as compared with the starting timerequired when using an unprocessed coppersilver screen.

The catalyst unit was filled with the compressed, annealed alternatecopper-silver screen catalyst, as described above, of the presentinvention. The particular catalyst unit used in this example containedover twenty-five alternate layers and in its compressed condition wasslightly over 3" inthickness. The unit was to be operated for convertingethyl alcohol to acetaldehyde. In order to place the unit in operationit is necessary to heat the unit up to about 932 F. or such temperatureas may be necessary to start operations when the alcohol and air are fedin. This auxiliary heating for starting the apparatus was accomplishedby supplying the combustion products from burning producer gas to heatthe catalyst screens up to suflicient temperature for initiatingreaction. After a thermocouple showed a temperature from 662 F. to 842F. within the catalyst until a mixture of commercial ethyl alcohol andair, preheated and in a vaporous condition, was introduced into the unitbelow the catalyst screens. Upon contacting the catalyst that had beeninitially warmed by auxiliary heating, conversion of the alcohol toacetaldehyde took place. In less than one hour the unit was operating ina self-sufilcient manner, the catalyst being kept up to temperature bythe exothermic heat of the reaction, all auxiliary heating being cutoff. Also within the hour the feed of the alcohol was increased tonormal production amounts and the conversion per pass of the alcohol toacetaldehyde at the end of the hour exceeded 50%. In starting the sameunit in prior instances with catalyst unprocessed in accordance with thepresent invention several hours were required to get the unit intooperation before desired conversion was attained and the auxiliaryheating could be cut off. v

Example II In accordance with this example a comparison was made of aunit containing the prior art type of screen with the same unitcontaining the present improved type of screen. The unit with the priorart type of screen operated over a period slightly greater than sixmonths before the decomposition products, as evidenced by carbonmonoxide and carbon dioxide in the effluents, exceeded a predeterminedstandard or 3%. In other words, when the content of the effiuent gascontains more than 3% carbon monoxide and carbon dioxide, this indicatedthat too great a portion of the feed was being lost throughdecomposition and that catalyst failure, from the economic standpoint,had occurred. The unit was shut down and the catalyst screen replacedwith an improved screen of the present invention. The unit was startedup as described in Example I, the same type of feed and other conditionsmaintained as before. However, after eight months operation the regularanalysis of the efliuents showed that the decomposition losses had notat that time exceeded 1%. Hence, it is apparent that the life of the newcatalyst is much longer than that of the older type.

Example III In accordance with this example, a comparison was made ofthe decomposition losses over a period of approximately six months on abattery of catalyst units which had been changed over to the improvedcatalyst screens in accordance with the present invention, with theprior six months operation of the same units when containing the oldtype catalyst. In other words, all

other conditionswere substantially the same. This comparison showed thatover 170,000 pounds of the ethyl alcohol feed was saved because thedecomposition losses'were that much lower. In addition the actualrecord'of the maintenance cost of these same units was several thousanddollars lower.

Example IV In accordance with this example a catalyst unit containingthe old type copper-silver, unprocessed screen was shut down after eightmonths operation, inasmuch as the decomposition products in theeffluents were greater than 3%. The unit was disassembled and thecatalyst screens subjected to five hours treatment at 900 F. in afurnace, in accordance with the present invention as described above.The catalyst screens thus treated were reassembled, compressed and theunit started up in accordance with Example I. After eight months ofcontinuous use the unit was still in operation and the analysis of theefiluents showed that the decomposition products had not exceeded 2%,although the conversion per pass of alcohol to aldehyde consistentlyaveraged greater than 35%.

At the end of eight months the unit was again shut down, the catalystscreens removed, again treated as above described, and the unitreassembled and placed in operation. The decomposition losses at the endof two months operation were below 1%, thereby showing that the catalystmay be repeatedly treated by the procedure of the present invention.

While in the foregoing examples, for convenience of illustration, ourinvention has been de scribed by reference to the conversion of ethylalcohol to acetaldehyde, in a similar manner propyl alcohol, butylalcohol and other organic Example V In accordance with this example theconversion of isopropanol to acetone was carried out. A generalapparatus arrangement for processing 3-4 carbon atom alcohols isdescribed in companion Hasche Patent 2,173,111. Hence, extendeddescription of general process and equipment details herein isunnecessary. It is sufilcient for the purposes of the present inventionto point out that screen catalysts as above described in the precedingexamples were contained in a catalyst unit. Isopropanol and air were fedto the lower side of the screen and in passing therethrough becameconverted to acetone. After operating the unit for a period thedecomposition products in the effluent gases amounted to over 1.1%,thereby indicating that losses were being encountered due to theisopropanol being decomposed into carbon monoxide and hydrogen. The unitwas stopped and the catalyst screens removed and subjected to a heatingat 1000 F. for two and one-half hours. This heating was in a furnace asalready described in detail above. After the heating the screens weresubjected to an air blast as already described for dislodging from thescreens any attached particles. The catalyst screens thus treated werereassembled with compression into the same catalyst unit and theprocessreinstituted (after the screens were brought to temperature, above 585F. by the use :of hot combustion products) by supplying isopropanol andair. 'Analysis of effluents showed that the decomposition products haddropped to 0.7% and that the liberated hydrogen from the conversion ofisopropanol to acetone had increased from about 14.2% to 16.6%. Thisindicated an increase in conversion of at least 3.7%. The unit with thisincrease in conversion operated continuously for ten months in theproduction of acetone from isopropanol before the decomposition productsagain exceeded 1.1%.

Example VI In accordance with this example a converter corresponding tothe converter of Example V and containing a similar screen catalyst wasemployed for the conversion of secondary butanol to methyl ethyl ketone.Approximately 67 units by weight of the secondary butanol were fed tothe unit per 24.-hour period. The unit was operated at a temperaturebetween 824 F. and 932 F. Analysis of the effluent gases indicated thatthe loss was approximately 3% due to carbon monoxide and carbon dioxideformation. moving and treating the catalyst screens at approximately1000" F. for 5 hours in the furnace described earlier, the screens werereassembled in the catalyst unit. Thereafter the catalyst unit wasbrought to temperature by means of intro duction of combustion gases andthen a feed of secondary butanol and air (about 5% axcess air) wassupplied thereto for producing methyl ethyl ketone. The loss due to theformation of decomposition products was then less than 1% and the unitwas operated for more than six months before the loss again exceeded 1%.

In a similar manner normal propyl alcohol was passed in contact withannealed screen catalyst of the present invention to give continuousproduction of a normal propylaldehyde. Likewise, normal butanol wasprocessed in contact with the annealed-compressed catalyst screens ofthe present invention to give continuous high yields of normalbutyraldehyde over extended periods of operation. The exact temperatureat which the alcohols may be contacted with the annealedcatalyst screenmay vary from 400 F. to 1200 F. and is not to be considered a limitationon the present invention. catalyst screen has been brought totemperature suihcient to cause reaction (by means of some ancillaryheating, such as the introduction of combustion gases) alcohol and airare fed against the catalyst screen and the process is sufficientlyexothermic to maintain the reaction. The temperature of the ancillaryheating may vary from 482 F. to 662 F.

While in the first portion of this specification we have describedour-invention primarily as carried out using a catalyst made up of bothcopper and silver members and prefer to use such a combination catalystfor economic and other reasons, the principles of the present inventionmay be applied where the catalyst is comprised of each copper andsilver. That is, we have found, recpecting catalysts comprisedprincipally or solely of copper or catalysts comprised principally orsolely of silver and when utilized for the conversion of lower aliphaticalcohols to the corresponding carbonyl derivatives, if such catalystshave been treated inaccordance with the present invention, that improvedresults may likewise be obtained. Further teachings respecting suchAfter are-- In other words, after the 8 E copper or silver may be hadfrom a consideration of the following examples:

Example VII In accordance with this example, a comparison was made of acatalyst unit operating on the conversion of ethyl alcohol toacetaldehyde, which catalyst unit contained only copper catalystscreens. These copper screens had not been treated in accordance withthe present invention. However the other conditions of operation weresubstantially the same as already described. It was found not readilypossible to operate such units with any degree of satisfaction whencopper screens of the untreated type were used. That is, thetemperatures were diificult to control and the decomposition was high asindicated by carbon dioxide and carbon monoxide in excess of 6% in theefliuent gas stream.

Upon replacing the aforementioned untreated copper screens with catalystscreens which had been heat treated at temperatures in excess of 500 F.for 3 to 15 hours, it was found that the temperature of operation forconverting alcohols to carbonyl compounds was relatively easilycontrolled. The carbon dioxide and carbon monoxide present in theeflluent gas stream was less than 3% even after three days of operation.Specifically in this example, the conversion of ethyl alcohol toacetaldehyde was approximately 27% with decomposition losses below 3%.Zhis indicated considerably lower decomposition than in the firstinstances where untreated copper screens were used.

Example VIII In accordance with this example a comparison between a unitacked with a1l-si1ver untreated catalyst screens was made with thefunctioning of a unit packed with all-silver catalyst screens which hadbeen treated in accordance with this invention. That is, in theoperation of the preferred unit the all-silver catalyst screens had beensubjected to heating for several hours at a temperature in excess of 500as already described in detail above, prior to assembling andcompressing thescreens in the catalyst unit. The feed of alcohol to theunits, the temperature of operation of the units, and the like details,were substantially the same in both instances.

The unit packed with'the all-silver untreated screens operated for aperiod of approximately three months. The decomposition products ofcarbon dioxide and carbon monoxide averaged about 0.8% at the start and3.9 at the finish.

In comparison therewith, the unit packed with the all-silver screenstreated in accordance with the present invention operated for a periodof seven months. The decomposition products of carbon dioxide and carbonmonoxide averaged 0.5% at the start and 0.7% at the finish.

It is thus apparent that the procedures of this invention improve thelife of units packed with either all-copper or all-silver screens anddecrease the formation of decomposition products when passing alcoholsover such catalysts as compared with operations wherein the catalystscreens are used as obtained and in an untreated condition.

While it is not desired to be bound by any theory of operation, thefollowing may be an explanation of the phenomena involved and may aid ina better understanding of the invention: It is apparent that, since theprocesses in which th improvement of the present invention takescatalytic processes employing catalysts of either 75 place are processeswherein large amounts of air have been continually fed, the presenttreatment goes beyond the mere oxidation of organic matter on thecatalyst by hot air as described in the aforementioned publications.Previous methods of cleaning the catalyst screens have also includedmechanically abrading the screen surfaces until they were visibly shinyand clean. However, such prior methods of removal of carbon and the likefrom the screens did not give the used screen restored activity. Hence,it may be that the treatment described herein functions to release ironoxide occluded with carbon particles, particularly in the pores of thescreen metal, as evidenced by the aforementioned analysis of thematerials dusted off the screens by means of a compressed air hose. Itmay also be that the relatively uniform heating under the conditionsdescribed herein releases certain internal strains in the catalystscreens thereby lengthening and making more uniform the catalyticactivity of the screens.

However, by Whatever the action, we have found a method of treatingcatalyst materials which readily lends itself to commercial adoptionwith good results, even with unskilled operators. While the treatment ofscreens has been described, as this is a common commercial typematerial, other physical forms of material such as netting, open meshwork, rods, pellets, and the like may be treated in a similar manner,and with equally satisfactory results.

We claim:

1. The process which comprises passing a lower aliphatic alcohol of atleast 2 carbon atoms and air into contact with a catalyst comprised ofalternate layers of pre-annealed copper and silver screens sufiicientlyopen to permit the ready passage of vapors of alcohol therethrough, saidscreens being compressed 2-6% of their uncompressed height, thepreannealing including heating the catalyst for several hours in anoxidizing atmosphere at a temperature above 500 F.

2. The process which comprises passing a lower aliphatic alcohol of atleast 2 carbon atoms and air into contact with a catalyst comprised ofalternate layers of preannealed copper and silver screens sufficientlyopen to permit the ready passage of vapors of alcohol therethrough butbeing compressed 2-6% of its uncompressed height, not more than 6 layersof the silver and copper screens being adjacent to one another, thepreannealing including heating the catalyst for several hours in anoxidizing atmosphere at a temperature above 500 F.

3. The process which comprises passing a vaporous mixture of air and alower aliphatic alcohol from the group consisting of ethanol, propanol,and butanol through a catalyst comprised of alternate layers ofpreannealed copper and silver screens sufficiently open to permit theready passage of the vapors of alcohol and air therethrough butcompressed 26% of its uncompressed height, the preannealing includingheating the catalyst for several hours in an oxidizing atmosphere at atemperature above 500 F.

4. The process for converting lower aliphatic alcohols of at least twocarbon atoms to their corresponding carbonyl derivatives in a rapid,uniform manner with high conversion which comprises contacting saidalcohol in the presence of a gaseous oxidizing medium and at atemperature between 400 F. to 1000 F. with screen catalyst essentiallycomprised of at least one metal from the group consisting of copper andsilver, said catalyst being characterized in that it has prior to usebeen processed in an oxidizing atmosphere for between three to fifteenhours at a temperature between 500 F. to 1500 F. whereby decompositionlosses of the alcohol fed or the carbonyl compound produced to carbonmonoxide or carbon dioxide are less than 3%.

5. The process for converting ethyl alcohol to acetaldehyde in a rapid,uniform manner with high conversion which comprises contacting saidalcohol in the presence of excess gaseous oxidizing medium and at atemperature above 400 F. with a screen catalyst essentially comprised ofa metal from the group consisting of copper and silver, said catalystbeing characterized in that it has prior to use been processed in anoxidizing atmosphere for between three to fifteen hours at a temperaturebetween 500 F. to 1500 F. and thereafter compressed.

6. In a process which comprises passing a lower aliphatic alcohol of atleast 2 carbon atoms and air through a screen catalyst, said screenbeing at a sufficiently high temperature to cause the conversion of thealcohol to a carbonyl compound and passing the alcohol through thescreen until the efiiuent gases show greater than 3% carbon monoxide andcarbon dioxide, the improvement steps which comprise discontinuing thepassage of alcohol and air through the catalyst screen essentiallycomprised of a metal from the group consisting of copper and silver andsubjecting the catalyst screen to an annealing treatment for severalhours at a temperature between 500 F. and 1500 F., in an atmosphereobtained by burning hydrocarbon fuel in the presence of excess air,thereafter returning the annealed catalyst screen to the process andpassing alcohol and air in contact therewith, whereby losses due tocarbon monoxide and carbon dioxide formation are reduced tosubstantially below 3%.

'7. In a process which comprises passing ethanol and air through ascreen catalyst, said screen being at a sufii-ciently high temperatureto cause the conversion of the ethanol to acetaldehyde and. passing theethanol and air through the screen until the eflluent gases show greaterthan 3% carbon monoxide and carbon dioxide, the improvement steps whichcomprise discontinuing the passage of ethanol and air through the screencatalyst essentially comprised of a metal from the group consisting ofcopper and silver and subjecting the catalyst screen to an annealingtreatment for three to fifteen hours, at a temperature between 500 F.and 1500 F., in an atmosphere obtained by burning hydrocarbon fuel inthe presence of excess air, thereafter returning the annealed catalystscreen to the process and passing ethanol and air in contact therewith,whereby losses due to carbon monoxide and carbon dioxide formation arereduced to substantially below 3%.

References Cited in the file 01' this patent UNITED STATES PATENTS OTHERREFERENCES Ellis, The Chemistry of Petroleum Derivatives, vol. II, pages878-880 (1937), Reinhold Publishing C'orp., New York.

1. THE PROCESS WHICH COMPRISES PASSING A LOWER ALIPHATIC ALCOHOL OF ATLEAST 2 CARBON ATOMS AND AIR INTO CONTACT WITH A CATALYST COMPRISED OFALTERNATE LAYERS OF PRE-ANNEALED COPPER AND SILVER SCREENS SUFFICIENTLYOPEN TO PERMIT THE READY PASSAGE OF VAPORS OF ALCOHOL THERETHROUGH, SAIDSCREENS BEING COMPRESSED 2-6% OF THEIR UNCOMPRESSED HEIGHT, THEPREANNEALING INCLUDING HEATING THE CATALYST FOR SEVERAL HOURS IN ANOXIDIZING ATMOSPHERE AT A TEMPERATURE ABOVE 500* F.